1. Field of the Invention
The present invention relates to an indication display unit for vehicles including indicators for indicating operational information such as vehicle speed, engine speed, residual fuel quality, time and other warnings, and also including a reflecting member having a reflecting surface on which indicated images by the indicators are reflected to allow the reflecting images to be visibly observed by a driver.
2. Description of the Related Art
Conventionally, there have been proposed various indication display unit for vehicles, a case in point being the one shown in FIG. 7.
This type of indication display unit is called a head-up display unit, wherein a projector 10 with its indicating surface directed upwards for indicating various information such as vehicle speed and so on is disposed in the dashboard 20, and the indicated image from the projector 10 is reflected on a half-mirror 30 which is disposed on the dashboard 20, whereby the virtual image 50 thereof, which is superposed on the external front view seen through the windshield 60, can be visibly observed from a visual point 40 at the driver's seat.
By use of the head-up display device as constructed above, the driver can observe the indicated image without turning his eyes toward various indicating meters, and an improved observability is thereby made possible.
Since the driver can visibly observe the external front view through a half-mirror because there is no hindrance caused to the driver's visual field with respect to the windshield, the aforementioned conventional device is optimum for a head-up display type unit. However, the half-mirror is rather weak either as itself or as a material to be constructed on the dashboard which is supposed to be firmly fixed thereon, and accordingly it is not easy to maintain the reflecting surface thereof in a stable position. In addition, since the indication light (or a light projected for indication) is reflected on two surfaces of the half-mirror, in the front and rear surfaces, there is a double image produced thereby, and this doubled image reflected on the half-mirror can be distinctly observed in some occasions, especially when the indicated image is substantially small, causing an inferior observability, and inferior quality of the indicated image itself.
Even though the indicated image is not fully superposed on the external front view as is done in the conventional device, a substantially similar effect to that of the head-up display using a half-mirror can be obtained, in which the indicated image is observed around the driver's visual field of the windshield, such as a nearby area of the upper surface of the dashboard.